First Principles Study on Ta₃N₅:Ti₃O₃N₂ Solid Solution As a Water-Splitting Photocatalyst

In this paper, we propose the new Ta3N5:Ti3O3N2 solid solution as a promising water-splitting photocatalyst. Using first principles computations, we study the phase stability, band gap, and band edge positions of the solid solution. The results suggest that the solid solution can likely be synthesized, and has a band gap lower than both its end members. The minimal band gap may be around 2.0 eV for a composition around 50%:50%, indicating that good efficiency under solar illumination may be achieved. In addition, the CB and VB of the solid solution are predicted to be bracketing the water redox levels, so the photocatalysis process is energetically favorable and bias voltage may not be required.